The new approach to one-step derivatization of saccharide with 5-(((2-(carbohydrazino)methyl)thio)acetyl)-aminofluorescein (C356) was described. In this approach, high fluorescent C356 was applied to label saccharide to enhance the response of derivative saccharide and high sensitive capillary high performance liquid chromatography with laser-induced fluorescence (Capillary-HPLC-LIF) associated with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was used to characterize C356 labeled saccharide. The effect of derivatization conditions was evaluated and discussed. The limit of detection (LOD) of neutral saccharide in our method attained the level of femtomolar. As a result, this method could be successfully applied to determine the structure of N-glycans of glycoprotein.